Many snakes produce highly toxic venoms, and toxins isolated from front-fanged snakes have been subjected to detailed biochemical and pharmacological studies. The biochemistry of venoms from colubrid rear-fanged snakes are poorly known, yet these snakes are abundant. Human envenomations are somewhat uncommon relative to envenomation by front-fanged snakes but appear to be increasing in frequency. Animal venoms have been and continue to be an important source of compounds for exploring human diseases (for example, clotting disorders, neurological diseases) and for use as biochemical probes of other systems such as neuromuscular communication, inteneuronal communication and blood clot cascade reactions. The proposed research will represent a systematic analysis of the venoms of several representative species of colubrids and will focus on toxic peptides and several enzymes present (or likely) in the venoms. Human envenomations often result in hemorrhage, necrosis or hemostatic changes, which suggests that several types of proteolytic enzymes/hemorrhagic toxins are present in the venoms. Phospholipase A2, a common component of animal venoms, is also likely to be found in these venoms; phospholipase A2 from these sources may be structurally different than those found in other snake venoms. Colubrid venoms represent a probable source of novel compounds or compounds with novel biological activities, and the proposed research will explore this possibility. The pilot study described herein will provide the data necessary for a larger investigation of the toxic components found in colubrid and other snake venoms; future research will focus on mechanistic aspects. Colubrid venoms represent a diverse, largely untapped source of new compounds, and this study will identify similarities and differences of toxins from colubrid venoms to toxins from the venoms of front-fanged snakes. A better understanding of the toxic components of these venoms will assist in the development of more effective treatments of snakebite, and toxins useful as biochemical tools may be discovered as well.